In the field of preparation and use of lightweight cementitious materials, such as so-called lightweight concrete, the materials that have been available to the trades up until now have generally required the addition of various constituents to achieve a strong but lightweight concrete mass that has a high homogeneity of constituents and which is uniformly bonded throughout the mass. Of the methods known to the inventor, there have been several patents issued relating to the inclusion of expanded polystyrene beads of an average bead size of about 20 mm diameter (about 20,000 microns) that are expanded by various heating methods either before the beads are introduced into the concrete mixture, or expanded after they have been added to the concrete mixture. It is an object of this invention to provide for a pourable, lightweight cementitious mixture that does not rely on expanded polystyrene for weight saving properties and strength. It is another object of the present invention to provide for a pourable, lightweight cementitious mixture that can be used in the construction of molded roofing tiles. It is yet another object of the present invention to provide for a pourable, lightweight cementitious mixture that can be used in the construction of laminated building foundations. It is yet another object of the present invention to provide for a pourable, lightweight cementitious mixture that resists insect infestation and deterioration. Yet another object of the present invention is to provide for an extrudable cementitious mixture that can be extruded through various extrusion dies and can be cured without further shape manipulation or formation. Still another object of the invention is to provide for a cementitious mixture that can be molded under high pressure and readily ejected from the mold with a minimum of green time to enable rapid recycling of the mold.
The present invention achieves these objectives through the use of micronized particulates of polystyrene in a cementitious mixture composition having very low water concentrations.